This is a working overview of HPLC assay, written for readers who want more than a one-paragraph summary but less than a textbook.
This page was last updated on 2025-12-05 and is reviewed periodically as new material appears.
The compound was identified in the nineteenth century after chemists isolated a nitrogenous substance from meat extracts. Later work established its role in muscle energy metabolism and its conversion to phosphocreatine. Chemical synthesis of creatine followed, and industrial production made the monohydrate widely available as a purified powder. Interest expanded in the late twentieth century when researchers began studying creatine supplementation and muscle physiology. Historical accounts sometimes differ on exact dates and attributions, but the broad sequence from tissue extracts to synthetic production is well documented.
In the body, creatine is obtained from dietary meat and fish and is also synthesized from arginine, glycine, and methionine. Muscle stores creatine and phosphocreatine, which participate in the rapid regeneration of adenosine triphosphate during short, intense activity. The monohydrate form is used in research because it is chemically defined, stable as a dry solid, and relatively inexpensive to produce. Questions remain about whether other creatine forms offer meaningful advantages in absorption or tissue retention, and findings vary across studies and populations.
Creatine monohydrate is a crystalline compound formed from creatine and one molecule of water. Creatine itself is a nitrogen-containing organic acid that occurs in vertebrate muscle and other tissues. The monohydrate designation refers to the water included in the crystal lattice, not to water added during manufacturing. Its chemical formula is commonly written as C4H9N3O2·H2O. The solid is typically a white, odorless powder with low solubility in water at room temperature. It is one of several creatine forms described in scientific and commercial literature.
Creatine monohydrate is a crystalline compound formed from creatine and one water molecule in its solid lattice. Creatine itself is a nitrogen-containing organic acid involved in energy transfer in muscle and other tissues. The monohydrate form is the most common solid form used in research and commercial products because it is stable and easy to handle. The term "monohydrate" refers to the fixed one-to-one ratio of water to creatine in the crystal, not to moisture content. This distinction matters when comparing labels or calculating creatine content.
In chemical terms, creatine monohydrate is often described as N-(aminoiminomethyl)-N-methylglycine monohydrate, though nomenclature varies. Its solid state consists of zwitterionic creatine molecules linked with water through hydrogen bonding. The compound dissolves in water, but dissolution rate depends on particle size, temperature, and agitation. Once dissolved, the hydrate water becomes part of the solvent, leaving free creatine in solution. The monohydrate is not the same as creatine anhydrous, which lacks the water of crystallization and has a higher creatine fraction by mass.
Commercial creatine monohydrate is typically a white to off-white powder with low odor. It is commonly sold as a fine powder, micronized powder, or larger crystals, but these are physical forms of the same chemical. Purity grades vary, and products may contain small amounts of related substances such as creatinine, dicyandiamide, or moisture. The monohydrate is often selected for supplements and research because its production is well established and its behavior in water is predictable. Analytical certificates usually report assay, loss on drying, and heavy metals.
| Property | Value | Notes |
|---|---|---|
| Chemical formula | C4H9N3O2·H2O | Monohydrate includes one water molecule per creatine molecule |
| Molar mass | 149.15 g/mol | Value for the monohydrate; anhydrous creatine is about 131.13 g/mol |
| Appearance | White crystalline powder | Odorless or nearly odorless in purified form |
| Solubility in water | About 13 g/L at 25 °C | Solubility increases with temperature and varies with pH |
| Common synonyms | Creatine hydrate; N-(aminoiminomethyl)-N-methylglycine | Monohydrate distinguishes it from anhydrous creatine |
In aqueous solution, creatine monohydrate undergoes a slow conversion to creatinine, a cyclized degradation product. This reaction is pH- and temperature-dependent, and it proceeds faster in warm or alkaline conditions. Because the conversion is gradual, analytical measurements of creatine in solution must account for time and storage history. The equilibrium favors creatinine more strongly at higher temperatures, which is relevant to sample handling in laboratories and to beverage formulations. Refrigeration slows but does not entirely stop this process.
Quality assessment of creatine monohydrate typically uses high-performance liquid chromatography to separate creatine from creatinine and other impurities. Other methods include nuclear magnetic resonance spectroscopy, titration, and infrared spectroscopy for identity confirmation. Purity is often reported as a percentage of the labeled compound on a dry basis, while moisture content is measured separately. Because different analytical methods have different selectivity, comparing purity values across sources requires attention to the method and sample preparation.
In dry solid form, creatine monohydrate is relatively stable when protected from moisture and heat. The crystal lattice includes water, and exposure to high humidity can cause caking or gradual changes in powder flow. Elevated temperatures may accelerate decomposition, particularly if moisture is present. Studies generally report that sealed, dry material retains acceptable purity for extended periods, although exact shelf life depends on packaging and storage conditions. Light exposure is not usually considered a major factor for this compound.
Quality control of creatine monohydrate relies on a combination of identity, purity, and moisture tests. High-performance liquid chromatography with ultraviolet detection is widely used to separate creatine from creatinine and other related nitrogenous compounds. Spectroscopic methods such as infrared and nuclear magnetic resonance provide structural confirmation. Because the material is a hydrate, water content is measured separately, often by Karl Fischer titration. These tests together establish whether a lot meets a defined specification.
Manufacturing processes can leave trace amounts of dicyandiamide, creatinine, or residual solvents, depending on the synthetic route and purification steps. Heavy metals, arsenic, and microbial contamination are also monitored for food or pharmaceutical grades. Particle size distribution can affect dissolution behavior and blending uniformity, so it may be specified for certain applications. Analytical results are reported on a dry basis or as-is basis, and the difference matters when comparing certificates of analysis. Open questions remain about how minor impurities influence long-term stability under varied storage conditions.
Stability studies typically examine the effects of temperature, humidity, and light on creatine monohydrate. Sealed containers stored in cool, dry conditions help limit moisture uptake and hydrolysis. Elevated temperature and high relative humidity can accelerate conversion to creatinine, especially in aqueous solutions. In solid dosage forms, excipients and processing steps may also affect stability. Published stability data are not fully consistent across studies because test conditions and analytical methods vary.
Solid creatine monohydrate is generally stable when kept cool and dry, but it can hydrolyze to creatinine over time. Moisture, heat, and acidic conditions accelerate this conversion, which reduces assay values and changes the material's properties. Creatinine is a cyclic dehydration product that is also a normal human metabolite, so its presence in a sample is not necessarily a health concern by itself. In quality testing, creatinine is monitored as a marker of degradation and purity.
Identity and purity are assessed with several complementary methods. High-performance liquid chromatography can separate creatine from creatinine and related impurities, often with ultraviolet detection. Nuclear magnetic resonance and infrared spectroscopy provide structural confirmation, while Karl Fischer titration measures water content. Elemental analysis and mass spectrometry may be used for additional confirmation, especially in research or forensic settings. No single method captures every quality attribute, so laboratories typically combine results and compare them against a specification.
Creatine monohydrate is sold as a dietary ingredient in some countries and as a food supplement in others. Regulatory frameworks vary, so purity limits, labeling rules, and permitted claims are not globally uniform. In the United States, it falls under dietary supplement rules, whereas the European Union treats it as a food supplement ingredient. Pharmacopeial monographs, where they exist, can provide public quality standards, but not every product is required to meet them. Questions about long-term effects and patterns of use remain areas of active study rather than settled regulatory findings.
Kräusening Kräusening ( KROY-zen-ing) is a conditioning method in which fermenting wort is added to the finished beer. The active yeast will restart fermentation in the finished beer, and so introduce fresh carbon dioxide; the conditioning tank will be then sealed so that the carbon dioxide is dissolved into the beer producing a lively "condition" or level of carbonation. The kräusening method may also be used to condition bottled beer.
In 2019, the non-profit labor justice organization Fair World Project released an article outling how despite Starbucks had passed coffee producers as slave free in their Brazil production units using their internal C.A.F.E. certification standards, that Brazilian labor inspectors had proof of child slave labor practices being present in their supply chain. In 2022 Starbucks announced that they were going to stop certifying their coffee beans as fairtrade, in favor of their own in-house investigations.
Charles Frank Farthing CF (22 April 1953 – 6 April 2014) was a New Zealand doctor who specialised in the treatment of AIDS. He was the medical director of the AIDS Healthcare Foundation from 2001 to 2007. He later worked at Merck Sharp & Dohme as the director of medical affairs for infectious diseases in the Asia-Pacific.
Sources: en.wikipedia.org
== Composition and nutrition == Garlic powder is 73% carbohydrates (including 9% dietary fiber), 17% protein, 1% fat, and 6% water (table). In a reference amount of 100 g (3.5 oz), garlic powder supplies 331 calories, and is a moderate-to-rich source (higher than 10% of the Daily Value, DV) of several B vitamins and dietary minerals (table).
=== EC 2.7.2: Phosphotransferases with a carboxy group as acceptor === EC 2.7.2.1: acetate kinase EC 2.7.2.2: carbamate kinase EC 2.7.2.3: phosphoglycerate kinase EC 2.7.2.4: aspartate kinase EC 2.7.2.5: Now EC 6.3.4.16, carbamoyl-phosphate synthase (ammonia) EC 2.7.2.6: formate kinase EC 2.7.2.7: butyrate kinase EC 2.7.2.8: acetylglutamate kinase EC 2.7.2.9: Now EC 6.3.5.5, carbamoyl-phosphate synthase (glutamine-hydrolysing) EC 2.7.2.10: phosphoglycerate kinase (GTP) EC 2.7.2.11: glutamate 5-kinase EC 2.7.2.12: acetate kinase (diphosphate) EC 2.7.2.13: Now known to be due to the activities of EC 6.1.1.17, glutamate—tRNA ligase, EC 1.2.1.70, glutamyl-tRNA reductase and EC 5.4.3.8 glutamate-1-semialdehyde 2,1-aminomutase EC 2.7.2.14: branched-chain-fatty-acid kinase EC 2.7.2.15: propionate kinase EC 2.7.2.16: 2-phosphoglycerate kinase EC 2.7.2.17: [amino-group carrier protein]-L-2-aminoadipate 6-kinase EC 2.7.2.18: fatty acid kinase
=== Homonuclear nuclear magnetic resonance === With unlabelled protein the usual procedure is to record a set of two-dimensional homonuclear nuclear magnetic resonance experiments through correlation spectroscopy (COSY), of which several types include conventional correlation spectroscopy, total correlation spectroscopy (TOCSY) and nuclear Overhauser effect spectroscopy (NOESY). A two-dimensional nuclear magnetic resonance experiment produces a two-dimensional spectrum. The units of both axes are chemical shifts. The COSY and TOCSY transfer magnetization through the chemical bonds between adjacent protons. The conventional correlation spectroscopy experiment is only able to transfer magnetization between protons on adjacent atoms, whereas in the total correlation spectroscopy experiment the protons are able to relay the magnetization, so it is transferred among all the protons that are connected by adjacent atoms. Thus in a conventional correlation spectroscopy, an alpha proton transfers magnetization to the beta protons, the beta protons transfers to the alpha and gamma protons, if any are present, then the gamma proton transfers to the beta and the delta protons, and the process continues. In total correlation spectroscopy, the alpha and all the other protons are able to transfer magnetization to the beta, gamma, delta, epsilon if they are connected by a continuous chain of protons. The continuous chain of protons are the sidechain of the individual amino acids.
Susan M Gaines is an American writer. She is the author of the novels Accidentals (2020) and Carbon Dreams (2001), and co-author with Geoffrey Eglinton and Jurgen Rullkötter of the science book Echoes of Life: What Fossil Molecules Reveal about Earth History (2009). Her short stories have been nominated twice for the Pushcart Prize. She is a former fellow of the Hanse Institute for Advanced Study in Germany. In 2018, she was awarded a Suffrage Science Award for women in science and science writers who have inspired others.
Sources: en.wikipedia.org
The report that CMS requires labs to prominently display complaint posters instructing lab workers how to file anonymous complaints. In a July 2007 response to the GAO, CMS said that it lacked the legal authority to mandate labs to display posters. They plan to take several other steps to increase awareness of complaint processes including: (1) posting fact sheet on the CMS web site on complaint filing (2) adding information on filing complaints to the interpretive guidelines used by surveyors (3) adding complaints received by accrediting organizations to their complaints database and (4) reminding states and accrediting organizations by letter about the importance of complaints. CMS reported that it sent a letter about complaint tracking to accreditation organizations, exempt states, and professional laboratory organizations on November 30, 2007. According to CMS, this letter highlighted the importance of complaint tracking and filing, and encouraged the publication of compliant processes. CMS has also developed a CLIA Brochure on Complaints, which was being prepared for release as of September 2008. Once released, CMS anticipates posting the brochure on its website and printing copies for distribution to laboratories. We will continue to monitor the implementation of this recommendation. In 2009, the GAO recommended that CMS require all survey organizations to develop and require labs to prominently display posters instructing lab workers how to file anonymous complaints.
Hydromorphone, also known as dihydromorphinone, and sold under the brand name Dilaudid among others, is a morphinan opioid used to treat moderate to severe pain. Typically, long-term use is only recommended for pain due to cancer. It may be used by mouth or by injection into a vein, muscle, or under the skin. Effects generally begin within half an hour and last for up to five hours. A 2016 Cochrane review (updated in 2021) found little difference in benefit between hydromorphone and other opioids for cancer pain. Common side effects include dizziness, euphoria, sleepiness, nausea, itchiness, and constipation. Serious side effects may include abuse, low blood pressure, seizures, respiratory depression, and serotonin syndrome. Rapidly decreasing the dose may result in opioid withdrawal. Generally, use during pregnancy or breastfeeding is not recommended. Hydromorphone exerts its effects by activating opioid receptors, mainly in the brain and spinal cord. Hydromorphone 2 mg IV is equivalent to approximately 10 mg morphine IV. Hydromorphone was patented in 1923. Hydromorphone is made from morphine. Hydromorphone is a therapeutic alternative on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2022, it was the 233rd most commonly prescribed medication in the United States, with more than 1 million prescriptions.
CD123), CLEC4C, and Neuropilin, and 5) failure to express certain marker proteins that are commonly expressed by myeloid, lymphoid, and NK cell lineages. Blastic plasmacytoid dendritic cell neoplasm typically arises after the serial acquisition of multiple genetic abnormalities in pDC or their precursor cells. Inactivating mutations (i.e. mutations which cause the gene to make no or a less active product) in the TET2 gene are the most common genetic abnormality in the disease, occurring in 32–67% of all BPDCN cases and often accompanied by mutations in either the NPM1 or SRSF2 gene. Numerous other genetic abnormalities are associated with the disease: 1) mutations in NRAS, ASXL1, and TP53; 2) deletions of the CDKN2A-ARF-CDKN2B locus on the short arm of chromosome 9, CDKN1B locus on the short arm of chromosome 12, RB1 locus on the long arm of chromosome 13, or NRC1 locus on the long arm of chromosome 5; 3) fusions of KMT2A on the long arm of chromosome 11 with MLLT1 on the short arm of chromosome 10, SUPT3H on the short arm of chromosome with MYC on the long arm of chromosome 8, or KMT2A on the long arm of chromosome 11 with MLLT1 on the long arm of chromosome 19; and 4) duplication or loss of entire chromosomes, particularly chromosomes 9, 13, or 15. Laboratory studies indicate that malignant pDC have a pathologically overactive NF-κB pathway that promotes their survival and production of various cytokines) that stimulate their own proliferation.
Sources: en.wikipedia.org
It is a crystalline form of creatine that contains one water molecule per creatine molecule. The compound occurs naturally in muscle tissue and is also produced synthetically for research and consumer products. The monohydrate label describes the solid's hydration state.
Creatine monohydrate contains creatine, but the two terms are not strictly interchangeable. The monohydrate includes water in the crystal, while creatine refers to the base molecule. Other creatine forms pair the molecule with different acids or carriers.
Dietary creatine is found mainly in meat and fish. The human body also synthesizes creatine from amino acids in the liver, kidneys, and pancreas. The monohydrate powder used in products is manufactured rather than extracted directly from food.
It is a solid form of creatine that contains one water molecule per creatine molecule in the crystal lattice. The hydrate water is part of the crystal structure rather than loose moisture. The term is often used for the common crystalline powder grade.